Pastels - Substrates, Methods, Materials and Conservation

I have never been so confused in reading information about pastel, lightfastness, fixative...and so on. Everyone seems to have a different opinion about everything. <Sigh>

Lesley Harrison, a professional pastel animal artist, has been painting with pastels for over 25 years states in her 2002 printed book,

"Pastels are the most permanent of all art mediums because there are no liquid binders that might cause them to darken, fade, yellow, crack or blister with time. These are pastel paintings that were created in the sixteenth century, and their colors are still as bright and vivid as the day they were painted."

Wende Caparole (Daniel Greene's wife) paints beautiful and detailed children portraits. In her book, 'Painting Childrens Portraits in Pastel' states, "

"Pastels are pure pigments and should not be touched or sprayed with fixative before framing. Touching or spraying the surface will damage the portrait."

Sharon wrote:

I spray! I have a copy of Daniel Greene's book "Pastel". He sprays to darken his pastels so he can layer lighter colors over his work. He is

So who is right? Daniel Greene doesn't have a problem in spraying his pastel paintings but why would his wife Wende?

I am in the learning stages of this medium (and color) but the opinions are scattered all over the place. Maybe I'm looking too far into this(?)

Ahhhh, I think I will have a glass of wine and start sketching with my pencils.